Evaluating Mansehra dolerite, northern Pakistan for high performance concrete applications: Insights from engineering and petrographic characteristics

The growing demand for durable high-performance concrete has highlighted the need for high quality coarse aggregates with strong mechanical and suitable mineralogical properties.In this study, the engineering and petrographic properties of Mansehra Dolerite (MD), a mafic intrusive rock from northern Pakistan, are investigated to evaluate its suitability as a high-strength aggregate for durable infrastructures.A total of 40 representative rock samples were collected from three key regions: Tanawal Area (Group A), Plura Area (Group B) and Oghi Area (Group C).The petrographic analysis of 25 samples from these three groups confirmed the doleritic nature of the rock, characterized by a dominant plagioclase (30-60 %) and clinopyroxene (20-40 %), with accessory orthopyroxene, hornblende, opaque minerals, and minor biotite, quartz, and chlorite.The rocks exhibit typical ophitic to sub ophitic textures with occasional porphyritic features, indicating slow crystallization in an intrusive environment.Petrographic screening indicates low Alkali Silica Reaction (ASR) potential; however, definitive confirmation requires performance based expansion testing standardized by American Society for Testing and Materials (ASTM C1260 and/or ASTM C1293/C1293M), which was not conducted in this study.The engineering tests revealed that the MD aggregates have excellent physical and mechanical properties, including low porosity (0.51-2.80 %), minimal water absorption (0.16-0.96 %), high specific gravity (up to 3.25), and high resistance to impact, crushing, abrasion, and weathering.Group A (Tanawal) samples consistently showed the highest quality, with the lowest impact strength value (4.1-10.5 %) and the lowest abrasion loss (8.5-13.4%), making them particularly suitable for construction and heavy concrete applications.These results indicate that Mansehra dolerite is a mechanically competent aggregate source, and petrographic observations suggest low ASR potential; Group A material shows the most favorable overall indices for high-strength concrete applications.